An unfailingly polite lady called to ask for help with a Windows installation that had gone terribly wrong. 
Customer: “I brought my Windows disks from work to install them on my home computer.” (Training stresses that we are “not the Software Police,” so I let the little act of piracy slide.)
Tech Support: “Umm-hmm. What happened?” 
Customer: “As I put each disk in it turns out they weren’t initialized.” 
Tech Support: “Do you remember the message exactly, ma’am?” 
Customer: (proudly) “I wrote it down. ‘This is not a Macintosh disk. Would you like to initialize it?'” 
Tech Support: “Er, what happened next?” 
Customer: “After they were initialized, all the disks appeared to be blank. And now I brought them back to work, and I can’t read them in
the A: drive; the PC wants to format them. And this is our only set of Windows disks for the whole office. Did I do something wrong?”